1. Field of the Invention
The present invention relates to a nitride-based compound semiconductor light-emitting device (light-emitting diode or the like, for example) capable of emitting light in the blue region to the ultraviolet region and a method of fabricating the same. More particularly, the present invention relates to an electrode structure of a nitride-based compound semiconductor light-emitting device from which a substrate is removed and a method of fabricating the same.
2. Description of the Background Art
A nitride-based compound semiconductor light-emitting device having a structure allowing extraction of electrodes from upper and lower portions and a method of fabricating the same are proposed in general (refer to Japanese Patent Laying-Open No. 2000-277804). As shown in FIG. 21, the nitride-based compound semiconductor light-emitting device disclosed in Japanese Patent Laying-Open No. 2000-277804 is obtained by bonding a conductive substrate 205 to a wafer of a semiconductor laminate 210 of nitride-based compound semiconductor layers formed by successively growing an n-type layer 200, an emission layer 201 and a p-type layer 202 on an insulating substrate and thereafter partially or entirely removing the insulating substrate from the wafer thereby exposing the semiconductor laminate 210 of the nitride-based compound semiconductor layers, while a negative electrode 206 and a positive electrode 207 are provided on the exposed semiconductor laminate 210 and the conductive substrate 205 as opposite electrodes respectively.
In the aforementioned conventional nitride-based compound semiconductor light-emitting device, however, a metal holding substrate is formed on the overall surface of the wafer to disadvantageously strain the semiconductor laminate 210 and break or crack the wafer, leading to reduction of the yield or reliability of the nitride-based compound semiconductor light-emitting device.
Further, the main surface of the p-type layer 202 forming the lower portion of the semiconductor laminate 210 and those of the conductive substrate 205 serving as a p-side holding electrode and the positive electrode 207 are identical to each other and hence the conductive substrate 205 and/or the positive electrode 207 disadvantageously blocks outwardly emitted light to reduce external luminous efficiency. In addition, the conductive substrate 205 and/or the positive electrode 207 formed by a metal layer disadvantageously reduces the outwardly emitted light, to result in deterioration of the external luminous efficiency of the nitride-based compound semiconductor light-emitting device.
Further, the n-type layer 200 may be also strained due to the negative electrode 206 directly formed thereon, to disadvantageously break or crack the wafer.